Instrument for drawing ellipses



April 1950 w. K. GROOME 2,504,832

INSTRUMENT FOR DRAWING ELLIPSES Filed Nov. 13, 1945 2 Sheets-Sheet 1 I N VEN TOR. wane K6000445- Arramsrzs' April 18, 1950 w, GRQQME 2,504,832

INSTRUMENT FOR DRAWING ELLIPSES Filed Nov. 13, 1945 2 Sheets-Sheet 2 qzd ydw Patented Apr. 18, 1958 UNITED STATES enses with: the len th sof -the, majpn q iameter Land c pe'ratirig'meansfoh the lopei ihgfm' scmber jfihitQand'. the s'fibportihg", megalns ,1 91; facilitati g @Jqcatihg of, the maj or sdiam'eterjfat ,desired ahgle .to thelinepf reference".

Othe'r -.fui*the'r ebjeets of. this inventionwill be p arent frqm thel followingldesci iption taken in connecti6h .wit'h the'ldragw'ings. in, vzhich:

Eigure' '1 is' aivertical tgahsyers'e tib thmugh theinstrument;

Figure 2 j at top pla nhyiew gnfwizhe, instrument {Figure is-atllalnSxzySh mriz n; f secfiio nt n t l 3+ ftFiguretl; v, s s H FigufeA is. relax elkayatipnalyiew of, the gen- .ierating' ain'ilan es!" 011? assembly;

' Eigurfi anibnd w .oithe generating arm and the em ilgassemply showri in-.Fi'gu 1e; 4=;}}ihd Figure aj's ide' elevegtbhal' yiewypfabeljtefiiig gin equjppedhwith 'a d up gate pf. the..sun.arm.

' .2 marked in degrees from0 to 360 9r @cldit ip n a,-11 y int r ree t fr m t to n, i te r l pk idi ec on t fac litat h tio i t h meJQ iax' l.a nf le inqline n an q pq i dilectidn ,5 jwithg'ejspe ct to th line Qf ,1jef ,e;*ehqe.

' Th ogel ati g' pigsqr iher unit I! ,gomprises e. sun arm I 2 which qapyxties the weight 9f the operati gpr scriberunittq the supportihg ring assem- .1y and, thiserm lffitt ot e 19 Rig l-,

1. 9 h PHO ItiIl fiQE h h su arn haw i'eferencemark'oh itgs ihqiqate H t lfi, Figm e '2, AV QKQa be; vi ed t ev r'nie lit s'amjt 'a L hQt QnlQ h n t h d l n nth supporfifig r i l fi .s wii fedit h L'l WQ ideo th im J zi asu he T u arm and the sun wheel are adJ st'ab lfq the s p n /B bu in th p er itii o th str 'tn'en fiy a l $1 dl in il fidjlj j ted plosiftliononth vs p or i tin 2e "The bo dy zq of the oiirati g or sprihe u it js rigidly cq hegted' to a n pperati ng shaft 22 "which passes through a d is yotatabvleflin the sunwl i'e el ,mhand'sm a mf I2"a, r 1d is supported oh"the suh 311m 12 hy a thrust washer 24 pinhed to' the oper- Z25 "ating'shait ilz ahdthus the smila'rm carries the "weight of all the moving parts'of the Unit. The ,s haft 22 is proviqed with a manipulating k c'ib ,261 1 The body 20 is qnstructgd to rceive the' sun body in he: ap le, n at lan w i h The ap lebgdyi 28 may jmfaql n t o 9. 9

21 ShOW LW Yiflflilltai fil m unt p h sharftlwi I H A s shqwn in Figure 3, the lowel faee of the capcircular scales, the "one desigpatgd' A bejin i Irectigns, fpr examplepf ,inches je nd is 'u secl to facilitate adjustment of the seegnd pla etayy 9 11 1 fi s pl netar whee fi 130.35% 1. 5 irib ,i nii is 1 an Q r strument) of the ellipse to be drawn and the other shown at B to indicate the zero angle position for the sun arm I2 on the supporting ring 5 for locating the major axis of the ellipse parallel to a line of reference. The divisions on the scale A are so spaced that each division space represents an equal increment in the length of the major axis.

The capsule body is held in the body of the unit by a holding plate 44 suitably secured to the lower face of the body of the unit and engaging under a shoulder 46 in the periphery of the lower end of the capsule body 28. The holding plate holds the capsule against a spring washer 48, the purpose of which is to provide enough thrust against the holding plate to hold the capsule in a locked position during the operation of the instrument. The capsule plate 32 is recessed at 49 to permit the capsule to be raised to free it for rotation for adjusting purposes.

The generating arm shown at 50, Figures 1 and 4, is fixed to the shaft 5| of the second planetary wheel 42 and carries the pencil holder assembly generally indicated at 52. Fixed to one end of the generating arm 50 is a thrust plate 54 which acts as a bearing for a shoulder 51 and a knob 58 on the adjusting screw 56. One side face of the generating arm 50' is provided with two scales, the one indicated at D to facilitate adjustment of the scriber unit for a given difference between the lengths of the major and minor axes of the ellipse to be drawn, and the other shown at M to aid in setting the unit by rotation of the capsule plate 32 for a given length of major axis of the ellipse to be drawn.

The pencil holder assembly 52 consists of the pencil body 60, the upper end of which is provided with a head 62 which is provided with flanges 64 having their opposed faces converging upwardly to cooperate with the upwardly converging side faces on the generating arm 50 to facilitate the movement and adjustment of the pencil assembly on the generating arm and to support and hold the pencil assembly normal to the generating arm.

Mounted in the pencil body 60 is a chucking section 66 on which is threaded a chuck thimble 88, and mounted within the pencil body and chucking section is a pressure spring for advancing the lead or the like H of the pencil. The chucking section is connected to the pencil body by a bayonet slot connection 12 to provide not only for the removal of the chucking section but also for freedom of movement of the chucking section vertically as the scriber moves over irregularities in the drawing board.

Suported on the head 62 of the pencil body is a spring 14 which consists of an arcuate portion I6 resting on the head 62 and with rounded holding detent portions 18 which cooperate with the threads on the screw shaft 56 to move the pencil assembly as the knob 58 on the adjusting screw 56 is turned to effect finaladjustmentof thel'lencil assembly on the generating arm '58. The spring 14 is provided with downwardly projecting ends 85 which may be pressed toward each other to release the spring from the adjusting screw 56 when it is desired to make a quick'approximate adjustment of the pencil holder assembly on the generating arm 50.

For the purpose of centering the instrument, a centering device shown in Figure 6 is provided. This includes a plate or arm IZa'of the same dimensions as the sun'arm l2. Secured to the arm lie is an operating knob 82 and a centering pin shaft 84 which, at its lower end, receives a centering pin 85 which may be clamped on the shaft by any well-known means as shown at 88.

Operation of the instrument In general in preparing the instrument for drawing an ellipse, the operating or scriber unit of the instrumentis first set for the desired shape and size of the ellipse. The supporting ring is then positioned by using the centering pin. Then the sun arm is properly positioned on the supporting ring after which the operating knob 26 is rotated to generate the desired ellipse.

Specifically, the pencil holder assembly is set to the diiference between the lengths of the major and minor axes by adjusting the pencil holder assembly along the generating arm and positioning it by means of the scale D. For example, for a one-half inch difference, the pencilrholder is positioned at the one-half A2) mark on the D Scale.

The pencil holder assembly is released for effecting this adjustment by pinching the spring 14 toward the body of the pencil holder and then sliding the assembly to the approximate setting. The spring 74 is then released, and the body of the'pencil holder is set to the exact mark by means of the knob 58 on the adjusting screw 58. The setting on the scale M that is directly above the setting on the scale D is then read as onequarter A1) inch. This represents the portion 1 axis. The capsule plate hasthe two scales A and B marked on it. The basic scale A'indicates the portion of the major diameter controlled by the angular position of the second planetary wheel 42 about the first planetary wheel 36, 38 and is calibrated in fractions of units of length such as inches, for example. The other scale B, which is superimposed on the scale A is calibrated'in degrees. This second scale indicates the angle to which the sun arm l2 must be positioned on the supporting ring 6 to maintain the zero angle position with the line of reference, of the major diameter of the ellipse to be scribed.

The supporting ringassembly is positioned by holding the two legs 8 and 9 which span the zero point against the T square or drafting machine scale. The zero angle of the major diameter will then be parallel to the edge of the T square or scale. The centering pin, Figure 6, is then placed on the supporting ring, and the supporting ring is moved bodily so that the pin is directly on the center of the ellipse to be drawn; or the point of the. centering pin while supported on the supporting ring rnaycbe engaged with a desired point on the paper and then the legs 8 and 9 may be lined up agai t theT- square. The centering pin is then remoy d and the adjusted operating or scriber unitis placed on the supporting ring with the reference mark on the sun arm in registration withthefdegree mark representing the angle indicated, on.th,e capsule plate directly radially of the jmark at which scale A is set. When the parts are so positioned. the direction of the major diameter will be parallel to the edge of the 1' square orscale.v If it is desired that the position of the major "axis be at ascents.

'amacute angle to the dine, or referencwthelsun:-

arm can-be rotated .with respect to :the indicated zero angle by an amount equal tosaid-r'angle in eitherydii'ection; dependingwupon-vthe direc tion of 1 inclination of thesmajor axis to the line of reference-- Thus, it is seenthat theonly' requirements, for

the use of the instrument are the differencesaof" the sun arm is held stationary I on the supporting ring assembly with-one hand, and the operating; knob 25-; is turnedwith the other hand to gene, 'erate the desired ellipse.-

While the invention has been *described'with reference to a preferred" embodiment illustrated;

it is to-be understood that I- reservetheright to all such changes as fall within the principlesof this; invention and'the scope of the appended claims;

I claim:

1'. An ellipsogra'ph comprising a suppcrtingring, asun, arm rotatable on said ring,- cooperating degree scale means on said ring and said sun arm, an operating shaft supported on and extending rotatably through said sun arm, a sun wheel secured to said sun arm, a planetary wheel supporting body secured to said shaft, a capsule frame unit; rotatably mounted in said body, a planetary wheel in said frame, unit engaging said ing said second planetary wheel journalledyin said frame unit parallel to said operating shaft and projecting below said frame unit, said frame unit comprising upper and lower sections defining'an external groove betweenthem, said lower section having a bottom face, and said body comprising two sections, on'elofwhich is narrower than and extends into said groove, concentric bottom face of the lower section of said frame unit, a scriber supporting arm secured to the lower end of the shaft of said second planetary wheel, a scriber adjustable longitudinally being provided with a lower scale to aid in positioning said scriber in accordance with the difference between major and minor diameters of an ellipse to be drawn, and with an upper scale readable in fractions of ellipse major diameter for indicating the setting to be given to said lower section of said frame unit by means of its fraction scale to add a length to the portion of the major diameter contributed by said scriloer to produce the total length of major diameter desired, and said degree scale on said lower section of said frame unit indicating the setting to be given to said sun arm to position the major diame er parallel to a line of reference.

2. An instrument of the character describedcomprising a supporting table, a sun arm rotatably mounted on said table, a capsule body, a shaft rotatable in said sun arm and connected to said body, a sun wheel surrounding said shaft and connected to said sun arm, a capsule mounted rotatably within said body on an axis parallel to said shaft, first planetary means rotatably mounted in said capsule on an axis coinciding with the axis of rotation of said capsule,

This isparticularly helpfulin.

second planetary means-rotatabl mounted in said capsuleoman axis eccentric to the axis-oi rotation :of' said capsule and: cooperating with said first: planetary means; a scriber' supporting arm rigidly connected-I tosaid second planetary means; and a scriber supported. for movement along the length ofsaid scriber arm;- said scriber arm being provided-with a scale for facilitating the adjustment of saidscriber :in accordance 1 with the difference between the-major and minor diameters of the ellipse tobe-'-drawn and with a cooperating scale to indicate the-portion of the length of the major diameter contributed by the adjustment of the vscriber, said capsule beingprovided with ascale' for facilitating adjustment of the second 'planetary means-- around the first planetary means to p'rovide for the remainder of: thelength ofthe majordiameter or the ellipse, and said-capsule being also provided with aadegree scale to indicate the position at which the sun arm should be=located-to bring the major diameter parallel to a line of reference for; anygiven adjustment ot-the secondplanetary means around the first planetary means-c 3. In an instrument ofthe'characterdescribed,

the'combination of asupporting-table provided with aplurality of-- supporting legs for positioning the table with respecttoa lineof reference, aneellipsograph supported'rotatablyon saidtable and provided with an index mark -said table being provided with degree marks forcooperation with said index -mark, saidellipsograph including a sun wheel, a-first planetary wheel cooperating with said--sun-wheel*and a-second planetary sun wheel, asecond planetary wheel cooperating Wheel cooperatingwith a fi P a y wheel, ascribes: arm rotatable with saidsecond planetary 'wheel 'and a scriberadjustable along the length of said arm; means -for=adjusting said second planetary wheelaround said first planetary wheel and indicating-means carried by said first-mentioned means for indicating, for different positions of said adjusting means, the angularposition to which saidellipsograph should be-set on-said tabletoinsure that the fractional length unit and degree scales on the majer P oflthfiempse" will: be drawn parallel to said line of reference.

4. In an instrument of the character described, the combination of a supporting table, an ellipsograph rotatably supported on said table and a1 Ong Said supporting arm Sam suppfirfing arm r provided with an index mark, said table being provided with degree marks for cooperation with said index mark, said ellipsograph comprising a sun arm rotatably supported on said table, a sun wheel rigid with said sun arm, a shaft rotatable in and extending through said sun arm and sun wheel and supported on said sun arm, a first rotatable planetary wheel supported by said shaft and cooperating with said sun wheel, a second rotatable planetary wheel supported by 4 said shaft and cooperating with said first planetary wheel, said second planetary wheel being revolvable about said first planetary wheel, a scriber supported by said second planetary wheel, means for facilitating rotation of said 3 shaft relatively to said sun arm and sun wheel,

graph rotatably supported on said table and provi'ded with an index mark, said ellipsograph comtable, a sun wheel rigid with said sun arm, a

shaft rotatable in and extending through said sun arm and sun wheel and supported on said sun arm, a first rotatable planetary wheel supported by said shaft and cooperating with said sun wheel, a second rotatable'planetary wheel supported by said shaft and cooperating with said first planetary wheel, said second planetary wheel being revolvable about said first planetary wheel, means for adjusting said second planetary wheel around said first planetary wheel and for maintaining said adjustment, a scriber supported by said second planetary wheel, means for facilitating rotation of said shaft relatively to said sun arm and sun wheel, and indicating means carried by said adjusting means for indicating, for different positions of said adjustingmeans, the angular position to which said ellipsograph should be set on said table to insure that the major diameter of the ellipse will be drawn parallel to a line of reference.

6. In an instrument of the character described, the combination of a supporting table, an ellipsograph rotatably supported on said table, and provided with an index mark, said table being provided with degree marks for cooperation with said index mark, said ellipsograph comprising asun arm rotatably and adjustably supported on said table, a sun wheel rigid with said sun arm, a shaft rotatable in and extending through said sun arm and sun wheel and supported on said sun arm, a first rotatable planetary wheel supported by said shaft and cooperating with said sun wheel, a second rotatable planetary wheel supported by said shaft and cooperating with said first planetary wheel," said second planetary wheel being revolvable about said first planetary wheel, means for adjusting said second planetary wheel around said first planetary wheel and for maintaining said adjustment, ascriber arm sup-. ported by said second planetary wheel and'carrying a scriber, means'for adjusting said scriber on said scriber arm, means for facilitating rotation of said shaft relatively :to said sun arm and sun wheel, and indicating means carried by said adjusting means for indicating, for different positions of said adjusting means, the angular position to which said ellipsograph should be set on said table to insure that the major diameter of the ellipse will be drawn parallel to a line of reference.

7. An ellipsograph comprising a support, a sun arm rotatable thereon, a sun wheel secured to said sun arm, a first planetary wheel cooperating with said sun wheel, a second planetary wheel cooperating with said first planetary wheel, means supporting said second planetary wheel for movement around said first planetary wheel, ascriber arm rigidly connected to said second planetary wheel, and a scriber adjustable along the length of said scriber arm, said scriberarm and said supporting means being provided with scales facilitating adjustment for the difference between the lengths of major and minor diameters and the length of the major diameter of the ellipses to be drawn, and said supporting means and said support being provided with degree scales to facilitate locating the major diameter in any desired angular relation to a line of reference.

WARREN K. GROOME.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

